JP2006153364A - Operation method of circulating fluidized bed combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method of a circulating fluidized bed combustion device capable of coping with new single-fuel combustion and mixed fuel combustion of various fuels only by implementing a test on typical conditions, and remarkably reducing labor hour and costs. <P>SOLUTION: In this operation method of the circulating fluidized bed combustion device wherein the fuel is burned in a combustion furnace while being fluidized with a bed material, and the bed material is externally circulated, combustion efficiency is estimated on the basis of volatile portions in fuel property, C/H ratio and C/O ratio, to be applied as an indicator of the operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a circulating fluidized bed combustion apparatus used for recovering combustion heat generated during incineration of municipal waste, industrial waste, etc., or combustion of fuel such as refuse solidified fuel (RDF). It relates to the driving method.

  In recent years, municipal waste, industrial waste, etc. have been increasing and their disposal has become a social problem. By incinerating these or using solid waste fuel as fuel The development of power generation equipment that recovers the combustion heat is underway.

  As one of the types of the power generation equipment, there is a circulating fluidized bed combustor, which, as shown in FIG. 4, is used as fuel such as municipal waste or garbage solidified fuel by the primary air A blown from the air dispersion nozzle 2. In a combustion furnace 1 that is combusted while being fluidized with a bed material 3 made of sand, limestone, or the like, and an exhaust gas that is connected to the upper part of the combustion furnace 1 and generated by combustion in the combustion furnace 1 The hot cyclone 4 as a medium separation device for collecting a fluid medium such as ash and sand, and the fluid medium collected by the hot cyclone 4 are introduced via the downcomer 5 to cool the fluid medium and flow An external heat exchanger 7 as an external recirculation unit that circulates back to the bottom of the combustion furnace 1 through a medium return pipe 6 and exhaust gas in which a fluid medium is collected by the hot cyclone 4 are introduced, It has a configuration in which the superheater 8 and economizer 9 is provided with a heat recovery unit 10 which is arranged.

  On the downstream side of the economizer 9 of the rear heat transfer unit 10, a gas air heater 12 for heating the air pressure-fed from the forced air blower 11 by the heat of exhaust gas is provided, and the air heated by the gas air heater 12 is The primary air A is supplied as primary air A to the bottom of the combustion furnace 1 through the primary air line 13, and the secondary air line 14 branched from the primary air line 13 is supplied to a required position in the vertical intermediate portion of the combustion furnace 1. The secondary air B is supplied, and the air fed from the flow air blower 15 is supplied to the bottom of the external heat exchanger 7 through the flow air line 18 as the flow air C. . In addition, a damper 16 for adjusting the flow rate of the primary air A is provided in the middle of the primary air line 13 on the downstream side of the branch portion of the secondary air line 14, and the secondary air B is in the middle of the secondary air line 14. A damper 17 for adjusting the flow rate is provided.

  The external heat exchanger 7 forms a wind box 21 for blowing the flowing air C upward from the air dispersion nozzle 20 at the bottom of the seal box 19 to which the downcomer 5 is connected. A final superheater 22 for generating superheated steam by heat exchange with the fluid medium and introducing it into the steam turbine is disposed in the upper seal box 19. Further, in consideration of the fact that the pressure in the lower part of the combustion furnace 1 is generally higher in the external heat exchanger 7 than the pressure in the lower part of the hot cyclone 4, the exhaust gas in the combustion furnace 1 is in this state. Is formed in a so-called siphon shape so that the flowing medium separated by the hot cyclone 4 can be surely flowed down into the combustion furnace 1 and returned to the downcomer 5 side of the hot cyclone 4. It is.

  In the circulating fluidized bed combustion apparatus as the power generation equipment as described above, the air fed from the forced air blower 11 is heated by the gas air heater 12 and supplied to the bottom of the combustion furnace 1 as the primary air A through the primary air line 13. At the same time, it is supplied as secondary air B to a required position in the middle of the vertical direction of the combustion furnace 1 through a secondary air line 14 branched from the primary air line 13 and is further fed under pressure from a flow air blower 15. Is supplied as flowing air C to the bottom of the external heat exchanger 7 through the flowing air line 18, and in this state, municipal waste, garbage solidified fuel, etc. are placed on the air dispersion nozzle 2 of the combustion furnace 1. When the waste is introduced, the waste is combusted while being fluidized together with the bed material 3 by the primary air A blown from the air dispersion nozzle 2.

  The exhaust gas generated by the combustion of the waste in the combustion furnace 1 is blown up together with a fluid medium such as ash or sand and introduced into the hot cyclone 4 where the fluid medium is collected and the hot cyclone is collected. The fluid medium collected by the cyclone 4 is introduced from the downcomer 5 connected to the lower part of the hot cyclone 4 to the external heat exchanger 7 as an external recirculation unit, and the external heat exchanger 7 removes heat to cool it. Then, it is returned to the bottom of the combustion furnace 1 through the fluid medium return pipe 6 and circulated.

  The exhaust gas from which the fluid medium has been separated by the hot cyclone 4 is guided to the rear heat transfer section 10, where heat is recovered in the superheater 8 and the economizer 9 of the rear heat transfer section 10, and further in the gas air heater 12. Then, it is discharged from the chimney to the atmosphere through a dust collector (not shown).

  On the other hand, the boiler feed water is heated by the exhaust gas in the economizer 9, flows through the steam drum (not shown) through the furnace wall 1 a of the combustion furnace 1, returns to the steam drum again, and becomes saturated steam to the superheater 8. The superheated steam introduced and superheated by the exhaust gas and superheated in the superheater 8 is guided to the final superheater 22 and further heated by the fluidized medium, and the superheated steam superheated in the final superheater 22 is introduced into the steam turbine. And power generation is performed.

  By the way, in the conventional circulating fluidized bed combustor as described above, when the operation is performed to singly or co-fire a new variety of fuels, a test is performed for each fuel under a wide range of conditions, and the fuel is discharged within a predetermined time. The fly ash is collected with a bag filter (not shown), and the combustion efficiency is calculated from the amount of the collected fly ash and the unburned carbon concentration.

As an example of the circulating fluidized bed combustion apparatus as described above, there is Patent Document 1, for example.
JP 2002-168423 A

  However, as described above, it has been a drawback that it is very laborious and costly to perform a test for each new multi-fuel and to determine the combustion efficiency each time.

  In view of such circumstances, the present invention is capable of dealing with the mono-combustion or mixed combustion of a new variety of fuels only by carrying out tests only on typical conditions, and the operation of a circulating fluidized bed combustion apparatus that can greatly reduce labor and cost. Is to provide a method.

The present invention is a method for operating a circulating fluidized bed combustion apparatus in which fuel is combusted while being fluidized with a fluid medium in a combustion furnace, and the fluid medium is externally circulated.
The present invention relates to a method for operating a circulating fluidized bed combustion apparatus characterized in that combustion efficiency is predicted based on the volatile content, C / H ratio, and C / O ratio in fuel properties, and used as an index of operation.

  In the operation method of the circulating fluidized bed combustor, the fuel co-firing rate is exothermic so that the volatile content in the fuel properties is 60% or more, the C / H ratio is 10 or less, and the C / O ratio is 15 or less. Adjustment on an amount basis is effective.

  According to the operation method of the circulating fluidized bed combustion apparatus of the present invention, it is possible to cope with the exclusive combustion or mixed combustion of a new variety of fuels only by carrying out a test only on typical conditions, and it is possible to greatly reduce labor and cost. The effects can be achieved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The present inventors conducted a test using a pilot-scale test apparatus substantially equivalent to that shown in FIG. The combustion furnace 1 was made of an external circulation type having an inner diameter of 0.36 [m] and a height of 15 [m] formed by a fireproof castable. The secondary air B was supplied from a position 4.3 [m] above the air dispersion nozzle 2. At the time of start-up, a bed temperature was preheated to about 973 [K] with a city gas burner (not shown), then waste as fuel was supplied from the feeder and switched to waste co-firing. For the bed material 3, sand having an average particle diameter of about 0.3 [mm] was used.

  There are five types of fuel used: waste tires, RPF (Refuse Plastic Fuel), wood chips, RDF, and coal, and their fuel properties are shown in FIG. The waste tire used what contained the metal wire as a reinforcing material. RPF is a compression-molded waste plastic or paper. RDF used was a domestic product of φ15 × 40 [mm]. The coal used was a high fuel ratio coal with a fuel ratio of 8.8. From the fuel properties of FIG. 1, the volatile content is highest in RPF, followed by wood chips, RDF, waste tires, and coal. The volatile content of coal is 9.0 [%], which is considerably lower than other fuels. The calorific value is highest for waste tires and lowest for wood chips.

  FIG. 2 shows the test conditions. Three types of samples were prepared: waste tires and RPF, RDF and coal, wood chips and RPF. The mixed firing rate was variously adjusted on a calorific value basis. The gas temperature in the furnace was in the range of 1073 to 1173 [K]. The combustion efficiency was calculated from the amount of fly ash collected and the unburned carbon concentration by collecting fly ash discharged within a predetermined time with a bag filter (not shown).

  As a result of organizing the test data, the relationship between the volatile matter in the fuel properties and the combustion efficiency tends to be a straight line having a slightly upward slope as shown in FIG. The relationship between the C / H ratio of the fuel and the combustion efficiency tends to be a straight line having a slightly downward slope as shown in FIG. 3 (b), and the relationship between the C / O ratio in the fuel properties and the combustion efficiency. It has been found that the relationship tends to be a straight line having a slightly downward slope as shown in FIG. In addition, the combustion efficiency of a vertical axis | shaft is shown by the ratio when the combustion efficiency of coal-fired combustion is set to 1.0.

  That is, it becomes possible to predict the combustion efficiency based on the volatile matter in the fuel properties, the C / H ratio, and the C / O ratio, and this can be used as an index of operation in the circulating fluidized bed combustion apparatus.

  For example, when using a fuel that has a low volatile content and a high C / H ratio or C / O ratio and cannot achieve the desired combustion efficiency, the volatile content is high and the C / H ratio or C / O ratio is high. Mix fuel with a low ratio.

  In this case, if the fuel co-firing rate is adjusted on a calorific value basis so that the volatile content in the fuel properties is 60% or more, the C / H ratio is 10 or less, and the C / O ratio is 15 or less, high combustion is achieved. Efficiency is obtained and is extremely effective.

  In this way, it is possible to deal with the mono-combustion or mixed combustion of a new variety of fuels only by conducting tests only on typical conditions, and labor and cost can be greatly reduced.

  Note that the operation method of the circulating fluidized bed combustion apparatus of the present invention is not limited to the above illustrated example, and it is needless to say that various changes can be made without departing from the gist of the present invention.

It is a graph which shows the fuel property used for the test for demonstrating an example of the form which implements this invention. It is a graph which shows the test conditions for demonstrating an example of the form which implements this invention. It is a diagram which shows the test result for demonstrating an example of embodiment which implements this invention, Comprising: (a) is a diagram which shows the relationship between a volatile matter and combustion efficiency, (b) is C / H ratio, and combustion FIG. 4C is a diagram showing the relationship between efficiency and (c) is a diagram showing the relationship between C / O ratio and combustion efficiency. It is a whole schematic block diagram which shows an example of the conventional circulating fluidized bed combustion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion furnace 2 Air dispersion nozzle 3 Bed material 4 Hot cyclone 5 Downcomer 6 Fluid medium return pipe 7 External heat exchanger 10 Rear heat transfer part

Claims (2)

An operation method of a circulating fluidized bed combustion apparatus in which fuel is combusted while being fluidized with a fluid medium in a combustion furnace, and the fluid medium is externally circulated,
A method for operating a circulating fluidized bed combustion apparatus, wherein combustion efficiency is predicted based on a volatile content in a fuel property, a C / H ratio, and a C / O ratio, and used as an index of operation.   The circulating flow according to claim 1, wherein the fuel co-firing rate is adjusted on a calorific value basis so that the volatile content in the fuel property is 60% or more, the C / H ratio is 10 or less, and the C / O ratio is 15 or less. Operation method of the bed combustor.

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